The function of PTCHD1 (patched domain containing 1, Ensembl gene identifier ENSG00000165186) is as follows. Required for the development and function of the thalamic reticular nucleus (TRN), a part of the thalamus that is critical for thalamocortical transmission, generation of sleep rhythms, sensorimotor processing and attention. Can bind cholesterol in vitro (PubMed:36769003). {ECO:0000250|UniProtKB:Q14B62, ECO:0000269|PubMed:36769003}.